Physical and Theoretical Chemistry

Biography

Biography: Dmitriy V Sotnikov

Abstract

The stracture of gold nanoparticles (GNPs) conjugates with four proteins (MW range 20-150 kDa and pI range 4-9) was studied. The composition of the conjugates was determined using the method of fluorescence spectroscopy according as it was previously proposed [Sotnikov D. V., et al. International Journal of Molecular Sciences. 2014. 16(1). 907-923]. Experimental results obtained in the framework of the Russian Science Foundation project (grant 19-14-00370) revealed regulations of mono- and multilayer immobilization of protein on GNP surface. At pH below the protein's pI, a positively charged protein molecules are attracted to the GNP and are easily conjugated to it forming a monolayer. When pH rises above pI, the negatively charged protein molecules are repelled from the surface. In this case, protein binding to the surface is possible due to donor-acceptor, van der Waals and other interactions. This effect is more pronounced for proteins with acidic pI. With increasing pH, the negative charge on the surface increases and, respectively, the layer of counter-ions near the particle increases. In addition, the sorption of the first layer leads to an even greater increase in the negative charge near the GNP surface and to the additional increase of the counter-ions layer. These processes provide an opportunity for negatively charged protein molecules to bind electrostatically to thicker cationic layer. According to asymmetrical flow field-flow fractionation data, increased pH does not enhance protein-protein interactions. Therefore, multilayer binding of proteins is caused by their interaction with the cationic coverage of GNPs.